Dr. Herbert Fredrickson, Dr. Elly Best and Dr . Dave Dr. Herbert Fredrickson, Dr. Elly Best and Dr . Dave Soballe Soballe U.S. Army Engineer R&D Center, Environmental U.S. Army Engineer R&D Center, Environmental Laboratory, Waterways Experiment Station, Laboratory, Waterways Experiment Station, Environmental Laboratory,Vicksburg, MS 39180 Environmental Laboratory,Vicksburg, MS 39180 - - 6199 6199 San Francisco Bay Mercury TMDL San Francisco Bay Mercury TMDL – – Implications for Constructed Wetlands Implications for Constructed Wetlands Tri Tri - - Service Infrastructure Conference Service Infrastructure Conference Water Quality Management Water Quality Management
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Dr. Herbert Fredrickson, Dr. Elly Best and Dr . DaveDr. Herbert Fredrickson, Dr. Elly Best and Dr . DaveSoballeSoballe
U.S. Army Engineer R&D Center, EnvironmentalU.S. Army Engineer R&D Center, EnvironmentalLaboratory, Waterways Experiment Station,Laboratory, Waterways Experiment Station,
Environmental Laboratory,Vicksburg, MS 39180Environmental Laboratory,Vicksburg, MS 39180--61996199
San Francisco Bay Mercury TMDLSan Francisco Bay Mercury TMDL ––Implications for Constructed WetlandsImplications for Constructed Wetlands
women greater than Federal health standards(UNC Asheville)
• 60,000 U.S.A. births per year Hg impaired (NAS,July 2001)
• Methylmercury (MeHg) is bioavailable form
Mercury – an EnvironmentalPollutant
Human Exposure Route - Mainly through eating fish
Fish Consumption Frequency Average Hg Hair Concentration(µg/g of hair)
None 2.0Less than 1 fish meal/month 1.4 (range 0.1 to 6.2)Fish meals twice/month 1.9 (range 0.2 to 9.2One fish meal/week 2.5 (range0.2 to 16.2)One fish meal/day 11.6 (range 3.6 to 24.0)
World Health Organization Programme for Chemical Safety
Cited in EPA’s Mercury Study Report to Congress December 1977
• MeHg accounts for 75% of USA fish advisories
• 2073 MeHg fish advisories in 41 states
Mercury – an EnvironmentalPollutant
Environmental Effects
San Francisco Bay Mercury TMDLSan Francisco Bay Mercury TMDL ––Implications for Constructed WetlandsImplications for Constructed Wetlands
SF Bay Mercury TotalMaximum Daily Load
(TMDL)GOALS:
1. Reduce total mercury loads into the bay.
2. Reduce methylmercury production.
3. Monitor and focus studies on understanding Bay system.
4. Encourage actions that address multiple contaminants.
California Regional Water Quality Control Boardhttp://www.swrcb.ca.gov/rwqcb2/sfbaymercurytmdl.htm
Mercury Total Maximum Daily Load(TMDL)
SF Bay Fish Tissue THg ConcentrationCompared to US EPA Criterion
µgTH
gpe
r gra
m w
et w
eigh
t
Leop
ard
shar
kSt
riped
bass
Whi
test
urge
onCa
lifor
nia
halib
utW
hite
croa
ker
Shin
ersu
rfper
ch
Jack
smel
t
1.6
0
3.5
0.5
0
Blac
k-ne
cked
stilt
sW
este
rnsn
owy
plov
erM
alla
rdSn
owy
egre
tBl
ack-
crow
ned
nigh
t her
onAm
eric
anav
ocet
Amer
ican
coot
Casp
ian
tern
CAcl
appe
r rai
lCA
leas
t ter
n
SF Bay Bird Egg THg ConcentrationCompared to No Effect Level
0.20.3
TMDL
California Regional Water Quality Control Boardhttp://www.swrcb.ca.gov/rwqcb2/sfbaymercurytmdl.htm
SF Bay Catchment - ~40% area of CA; 47% of CA runoff
Mercury Total Maximum Daily Load(TMDL)
Comparison of Rates of Atmospheric Mercury DepositionTotal Atmospheric Hg Depsition
0
5
10
15
20
25
30
ELA - Current N. Wisconsin Dorset, Ont. Florida Everglades Sweden West Coast(1987-89)
SF Bay
Locations
mic
rogr
ams
Hg/
m2/
year
Newly deposited Hg more bioavailable than that in sediment (Benoit et al, 2003)
National Atmospheric Deposition Program
Mercury Total Maximum Daily Load(TMDL)
Mercury TMDL Compliance Issue #1• Atmospheric deposition of mercury is an
important source.• States lack interstate regulatory jurisdiction
Mercury Total Maximum Daily Load(TMDL)
Mercury TMDL Compliance Issue #2
•• Linkages betweenLinkages between particulateparticulate THgTHg andandMeHgMeHg and fish body burdens are notand fish body burdens are notclear.clear.
•• NetNet MeHgMeHg production is site specificproduction is site specific•• MeHgMeHg uptake anduptake and biomagnificationbiomagnification isis
foodwebfoodweb specific.specific.
San Francisco Bay Mercury TMDLSan Francisco Bay Mercury TMDL ––Implications for Constructed WetlandsImplications for Constructed Wetlands
San Francisco BayWetland
Reconstruction“… the restored wetland be designed and operated tominimize methylmercury production and biologicaluptake, and result in no net increase in mercury ormethylmercury loads to the Bay.”
California Regional Water Quality Control BoardBasin Plan Amendment – Resolution R2-2004-008
•• Loss >90% of marsh wetlands since 1900Loss >90% of marsh wetlands since 1900
•• West coast flywayWest coast flyway
•• Critical habitat for endangered speciesCritical habitat for endangered species
California Clapper RailCalifornia Clapper Rail
Salt marsh harvest mouseSalt marsh harvest mouse
California Least TernCalifornia Least Tern
WetlandsWetlands UrbanUrban
San Francisco Bay Wetlands- Ecological Importance
Cumulative Effects of SF Bay Wetland Restorations
• HAAF represents only 203 hectares (0.8 %) of
26,300 hectares to be restored by 2055
• Many restoration sites will require fill material
• Intertidal wetlands are potential source of
MeHg
San Francisco Bay Area Wetlands Ecosystem Goals Project
Port of Oakland - Commercial ImportanceMost important on west coast ($30 B pa)
Deep Ocean Disposal Site
Potential Win – Win
1. Reduce DM disposal costs.
2. Avoid material & transport cost.
WalmartChina
Hamilton Army Airfield – FUDS Site
• HAAF will require <10 M yd3 of dredged material
• Upland disposal – Out of Bay (Hg Mass Balance)
China Camp State Park – Reference Site
SpartinaSpartinafoliosafoliosa
SalicorniaSalicorniavirginicavirginica
THg and MeHg in surface (0-4 cm) sediments from various wetlands
Aquatic Systems Produce MethylmercuryAquatic Systems Produce Methylmercury
�� Only a loose relationship between THg and MeHg levels (logOnly a loose relationship between THg and MeHg levels (log –– log plot).log plot).
�� Despite history of mining level of THg and MeHg are median amoDespite history of mining level of THg and MeHg are median among contaminated sites.ng contaminated sites.
�� However, potential for a 10X increase/decrease in MeHg levels.However, potential for a 10X increase/decrease in MeHg levels.
Benoit et al., 2003
1.5
350
HAAF/China CampFreshwater Wetlands
Marine & Estuaries
Lakes
Rivers
Regression
95% Prediction Interval
1,000
100
10
0.10
0.01
0.001
100 1000 100000.10 1.0 100000 1000000
log THg (ng/g)
log
MeH
g(n
g/g) 10
1.0
Mercury magnification in aquatic food websBiogeochemistry – Microbial Ecology
Question:
How do ppb levels of Hg in soil, water andsediment become ppm levels in top aquaticpredators? (Benoit et al., 2003)
Clues:
MeHg generally comprises <1% of the THg insoils and sediments, but comprises 99% of thetotal Hg in fish biomass.
Sulfate-reducing bacteria methylate mercury.
Gray et al., 2004 EST
HgHg2+2+bioavailablebioavailable
MeHgMeHg
BiomassBiomass
O2
+ Eh
SRB
- Eh
HgHg2+2+not bioavailablenot bioavailable
? ?
Food WebFood Web
Methylmercury is the species of highest concern
How Can We MinimizeHow Can We Minimize MeHgMeHg production?production?
• Bacteria in sediment catalyzeantagonistic methylation anddemethylation reactions.
• These reactions are veryrapid.
• The availability of mercury tomethylating bacteria limitsMeHg production.
High Primary ProductionHigh Primary Production –– Hallmark of Intertidal WetlandsHallmark of Intertidal Wetlands
SpartinaSpartinafoliosafoliosa
SalicorniaSalicorniavirginicavirginica
epipelonepipelon
San Pablo Bay WetlandSan Pablo Bay Wetland TrophicTrophic StructureStructure
. .
.
. .
GeukensiaGeukensia demissademissa
HemigrapsusHemigrapsusoregonensisoregonensis
NassariusNassarius obsoletusobsoletus
MeHgMeHg BiomagnificationBiomagnification at the Base of theat the Base of theFoodwebFoodweb
Mercury Bioaccumulation Factors (BAF)
Sample Site
THg
Tiss
ue/S
edim
entB
AFs
0.0
0.4
0.8
1.2
1.6
2.0
CrabMusselSnail
a
a b
b
THgSample Site
MeH
gTi
ssue
/Sed
imen
tBA
Fs
0
20
40
60
80CrabMusselSnail
HAAF-1 HAAF-10 China Camp
a
a
b
b
MeHg
HAAF-1 HAAF-10 China Camp
Use of Isotopic Ratios of C, N and S to UnravelUse of Isotopic Ratios of C, N and S to UnravelSan Pablo Bay WetlandSan Pablo Bay Wetland FoodwebsFoodwebs??